The red planet has gotten celebrity treatment this past year, with the touchdown of NASA's Phoenix Mars Lander in May, the continuing presence of the Mars Exploration Rover twins (Spirit and Opportunity) and NASA's Mars Reconnaissance Orbiter (which has imaged nearly 40 percent of the planet).

A major goal of such missions has been to find signs of past or present liquid water, the main ingredient for life. That's why Phoenix snagged a star-studded headline when the lander collected water ice near Mars' north pole this year.

Earlier in the year, Spirit found deposits of silica in Gusev Crater, suggesting, scientists said, that hot water once flowed through the Martian soil in hydrothermal vents.

As on Earth, these hydrothermal vents may have once harbored life. The discovered silica could preserve fossils of such ancient life if it did indeed exist there.

Just in from MRO - evidence of carbonates on the Martian surface. Since carbonates can't survive in acidic, harsh conditions, the mineral finding suggests any microbes crawling around when Mars was wet could've enjoyed a cushy existence.